Guest essay by Neil Catto
In view of the possible reasons for the 17-20 year global temperature plateau and further to Willis’ post a couple of weeks ago “Volcanoes Erupt Again”, I have been working on the same subject from a different angle.
I used volcano data from the Smithsonian Institute; http://www.volcano.si.edu/
As volcanic eruption particulates (aerosols) are said to affect global temperatures, it would suggest there must be a signature of this within the long term temperature record of the Central England Temperature (CET) http://www.metoffice.gov.uk/hadobs/hadcet/index.html
Volcanic activity is measured using a scale called the Volcanic Explosivity Index (VEI). This is a logarithmic scale between 0 and 8 although in modern times (~2000 years) there has been none over a 7.
Fig 1 significant volcanic activity (VEI 5-7) since 1 AD
Figure 1 shows significant volcanic eruptions occur regularly. However, as the scale is logarithmic (x10 after VEI 2) the impact of the major eruptions should be shown as VEI km^3, the volume of ejected particulates. A VEI of 0 is a non explosive eruption emitting <10,000m^3 or <0.0001 km^3 whereas a VEI of 7 emits 100 km^3.
Fig 2 significant volcanic activity (VEI km^3) since 1 AD
In figure 2 using km^3 shows the far larger impact of aerosol emissions from VEI 7 volcanic eruptions.
Fig 3 volcanic activity between 1659 and 2013 (CET timeline)
The scale of figure 3 was produced to show how large the Tambora eruption of 1812 was, but hides most of the lesser activity (VEI 0-5).
We must also remember for each year it is the total number of volcanic eruptions within that year shown as km^3.
Fig 4 volcanic activity, CET 1659-2013
In figure 4 the enormous explosivity of Tambora in 1812 is cut off, but the VEI 6 and VEI 5 can be observed. I highlighted Tarumae 1739 because in my research of the CET record it appeared a major influence on the temperature record falling from 9.2 Deg C to 6.84 Deg C between 1739 and 1740 and recovery to 9.3 in 1741.
Apart from Tarumae, my observations of figure 4 do not clearly indicate the relationship between volcanic eruptions and changes in temperature. As such I isolated the six major eruptions of VEI 6 or 7 (10-100 km^3) during the 1659-2013 period.
In the following six figures I have analysed the temperatures, a year prior to the eruption, the eruption year, and the years after the eruption until the temperature recovery date (=/> the previous year temperature).
I have also taken into consideration and highlighted the locations of the eruptions, either as Northern Hemisphere (NH) or Southern Hemisphere (SH).
Fig 5 Temperature recovery Long Island
Fig 6 Temperature recovery Tambora
Fig 7 Temperature recovery Krakatau
Fig 8 Temperature recovery Santa Maria
Fig 9 Temperature recovery Novarupta
Fig 10 Temperature recovery Pinatubo/Hudson
|
Volcano |
VEI |
Year |
Hemisphere |
Temperature Diff ° C Eruption-1yr |
Recovery Years (-1+x yrs) |
|
Long Island |
6 |
1660 |
SH |
+0.25 |
0 |
|
Tambora |
7 |
1812 |
SH |
-1.56 |
6 |
|
Krakatau |
6 |
1883 |
SH |
-0.43 |
1 |
|
Santa Maria |
6 |
1902 |
NH |
-0.28 |
1 |
|
Novarupta |
6 |
1912 |
NH |
-0.69 |
9 |
|
Pinatubo |
6 |
1991 |
NH |
-1.11 |
8 |
Table 1 summary of major volcanic eruptions temperature recovery:
Long Island (SH) shows no effect on a global scale.
Tambora (SH) could be said to have impacted global temperatures by a decrease of -1.56 Deg C, however within the recover period there was also a decrease between 1995/96 of -1.32 Deg C with no major volcanic activity above VEI 3.
Krakatau (SH) appears to have little effect on global temperatures, showing minor decrease of -0.43 Deg C and a recovery in a year. The temperature between 1884/85 fell by -1.26 Deg C with no greater than VEI 3.
Santa Maria (NH) again shows little impact on a global scale, even within the same hemisphere, with a drop of only -0.28 Deg C and a year to recover. The temperature dropped between 1903/04 by -0.32 Deg C with only one eruption of VEI 4.
Novarupta shows a fall of -0.69 Deg C, however within the recovery time there were falls of -0.67 Deg C between 1916/17 with one VEI5 (1916) and one VEI 4 (1917) and -1.03 Deg C between 1918/19 with only one VEI 4 (1918) and two VEI 4 (1919).
Pinatubo shows a fall of -1.11 Deg C, within the recovery time the temperature fell -1.32 Deg C between 1995/96 with no more than VEI 3 eruptions.
Discussion:
The effect of aerosol emissions on global temperatures from volcanic eruptions appears very small and may not be discernable from natural variation.
The effect of Tambora is shown in a Wiki at http://en.wikipedia.org/wiki/Year_Without_a_Summer
There is an effect from volcanic activity as shown that affected northern latitudes from Asia to Europe.
What about Zar Bomba, the 57 Megaton Russian bomb dropped on Nova Zembla september 1962 and the brutal 1962/63 winter in Western Europe?
The shockwave went around the earth three time and the mushroom cloud reached an altitude of 60 miles.
CET is not representative of global temperature, it is too subject to other influences, like AMO, and the other northern hemisphere cyclic phenomenon. Most of those large eruptions were near the equator, and the sulphate emissions would circulate in the equatorial winds. the cooling from El Chichon and Pinatubo only lasted for about two years. See:
http://notrickszone.com/2013/12/22/disappearing-excuses-aerosols-likely-not-behind-the-warming-pause/
Some high resolution temperatures from UAH. Daily Temps in the lower stratosphere and lower troposphere and volcanoes from Nov 1978 to Feb 2014.
http://s22.postimg.org/d2tpesoo1/Daily_UAH_LT_LS_Volcs_Feb14.png
Point is doesn’t show regularly in global records, so to say that the pause is volcanic is to cherry-pick your volcano.
But but but, all the non-eruptions we’ve had over the last 20 years is what’s kept AGWmanbearpig in check during “the pause”. I know, I read all about it!!! It was in print, it MUST be true!!!
Right?
Interesting work. Thanks. Once again we see the alarmists’ work and reality as contrasting systems.
Real data. What a concept. I believe the value here is to (once again) show that someone’s proposed ‘causation’ is barely even correlation. Or in this case, none at all.
Neil Catto
Nice article.
I have been reconstructing CET beyond its instrumental limit of 1659 and am currently at 1538.
see figure 11
http://judithcurry.com/2011/12/01/the-long-slow-thaw/
I have researched thousands of references relating to CET-many at the Met Office- and will shortly be posting an article tracing CET from 1200 to 1450AD.
I simply fail to see that volcanoes have any great effect on temperatures, other than perhaps for a season, for example the records of Exeter Cathedral show that the poor were given some funds to see them through a cold season that coincided with Laki.
However, most large volcanoes such as Michaels Mann’s one in 1257 simply fail to materialise in the crop records, indeed temperatures had dropped sharply several years before 1257 and recovered very quickly afterwards.
So other than a transient effect it is difficult to see Volcanoes as being a big factor, although it is the total optical depth of emissions that matters, which it is claimed remained very high for much of the LIA (thereby cooling it) whereas it did not figure in the MWP.(thereby allowing natural warmth)
I would back observations over models any day.
I must correct edcaryl who says:
March 11, 2014 at 7:47 am (Edit)
‘CET is not representative of global temperature, it is too subject to other influences, like AMO, and the other northern hemisphere cyclic phenomenon.’
Cet has a reasonable correlation of global temperature and a good one for the Northern Hemisphere. This has been noted by numerous climate scientists including Lamb and the Met office. There is a list of them in my article linked to above.
tonyb
VEI-7 eruption of Tambora started at 10 April 1815, not in 1812. About 160 cubic kilometer of stuff was ejected in two days. The next year was cold in Europe, with the worst famine of the 19th century. Mary Shelley had also written Frankenstein because of this. She spent the summer with friends at lake Geneva, but the weather was awful, so they had nothing better to do than to organize an indoors literary competition.
Tonyb
Thanks for your contributions. My understanding is that the CET record does not consist of raw data, so:
a) Are you comfortable with how the overall record has been prepared?
b) Is the method of preparation consistent over three and a half centuries?
SkS kidz are calling it the “faux pause”. LOL. It’s all down to those hiroshima bombs going off in the oceans at the rate of one-per-second. See, due to the magical properties of man’s CO2, the heat that was heating up our atmosphere is now heating the deep oceans instead. We can’t actually measure it, nor do we know how it gets there, or why it switches from heating the atmosphere to heating the deep oceans, but we “know” it’s there. And anyone who disagrees is just a d*nier.
James
Manley carried out a huge and painstaking job in reconstructing monthly CET to 1659 using many overlapping thermometers and other records. It is the most scrutinised temperature data set in the world.
Yes I am happy with it, as long as we recognise that all historic climate reconstructions should be subject to Hubert Lambs maxim that ‘We can understand the tendency but not the precision.”
I had the great pleasure of meeting David Parker at the Met office a couple of months ago who compiled the daily record to 1772
The one shortcoming-and one common with ALL instrumental records-is the location does sometimes alter, thereby introducing a warm or a cold bias. Personally, I think CET ran a few tenths of a degree too warm for the 1990’s due to the use of the warmer locations during that period
It is virtually indistinguishable from the 1730’s (according to Phil Jones) and personally I would find it of concern if Britons really had just lived through the warmest decade in our history!
tonyb
“The effect of aerosol emissions on global temperatures from volcanic eruptions appears very small and may not be discernable from natural variation.”
Indeed, this is difficult to disagree with, not to mention, what about the other 70% of the planet where volcanic activity occurs under water and adds heat to the oceans without airborn particulates or gases. This most certainly does not add to the “pause”. Detailed analysis of 30% of the story may be interesting but like most of the potentail climate causal variable data is very partial in nature.
@- Bruce Cobb
” We can’t actually measure it, nor do we know how it gets there, or why it switches from heating the atmosphere to heating the deep oceans, but we “know” it’s there.”
We know its there because we can, and have measured the continued expansion of the oceans for the last ~15 years and it is not magic but again a measured increase in pacific winds.
All these processes are objhectively observable and recorded just a short google from your desktop- (grin)
the problem with all these observational approaches to estimating the effect of volcanoes is this.
To get the real effect you would need to compare what the temperature would have been otherwise. You cant simply do that with observations. One might try by aligning time periods before and after the volcano, but unless you have a large sample the noise on either side of the eruption will make a good estimate hard to come by.
to get a Idea ( note I say Idea ) of how large the effect could be you have to run a model where the model provides the estimate of ‘what the temperature would have been had the volcano not occurred” You’ll end up with answers that appear to consistently over estimate the response.
Bottom line: observational studies cant answer the real question: which is
What is the difference between the temperature as recorded (observed) and the temperature it would have been had all other things been equal.? the only way to get the value of
“had all other things been equal” is to
A) run a simulation holding all other things equal
B) collect enough observations where the other conditions ( ocean cycles, solar forcings, etc) are effectively equal.
collecting enough samples for B will probably take more years than any of us have and “A” is not very accurate, although it suggests more effect than you see in inadequate observational studies.
Time to wheel out my volcano stack plots again:
http://climategrog.wordpress.com/?attachment_id=310
Follow links therein for other graphs and explanation of how it’s all derived.
http://climategrog.wordpress.com/?attachment_id=285
The weather in England depends on the direction it is coming from and the time of year. Perhaps it changes so as to cancel out the volcanic effect. Some sort of negative feedback.
“It is virtually indistinguishable from the 1730′s (according to Phil Jones) and personally I would find it of concern if Britons really had just lived through the warmest decade in our history!”
tonyb
The same was true of HISTALP records from austrian Alps, until they started ‘correcting’ it. Sadly they want to play hide and seek with the unadjusted data and the data on which the adjustments were made, so their long term rise is just more unverifiable, unscientific fiction.
Yet another potentially valuable dataset gets “homogenised” / corrupted beyond use.
I like to use this type of data in regard to climate geoengineering schemes. Just how many tons / Km^3 of stuff each year would be required to be shot how high in the air to affect a temperature drop. Then think of how much energy and cost it would take.
‘The effect of aerosol emissions on global temperatures from volcanic eruptions appears very small and may not be discernable from natural variation.’,
CO2 300,000 ppm but snowball Earth, followed by hot house Earth!but what about the co2 that was released in the past?
‘…geologists say the reason is very simple, the only part of the Earth not covered by ice was warm spots caused by VOLCANOES…but they did release gases..,co2 under normal conditions this would have reacted with rocks and rainfall and get washed out to sea…but in snowball Earth, there is no rain, no weathering…so the co2 just keeps building up…so you have high co2 levels with glaciers at the equator but this is a dynamic process, it doesn’t stay like this’ Potholer54
Now see for yourself!
Your Figure 1 nicely illustrates the point about volcanic cooling I made in my book, namely that it stays in the stratosphere and has no influence in the troposphere. The so-called “volcanic cooling” incidents on record are misinterpretations of accidental registration of an existing La Nina cooling with a theoretically predicted volcanic cooling. A good example is Pinatubo whose eruption coincided with an El Nino peak that was immediately followed by a La Nina cooling. That La Nina was quickly requisitioned as Pinatubo cooling and is still so designated on Roy Spencer’s temperature chart. The eruption of El Chichon, on the other hand, coincided with a La Nina valley that was immediately followed by an El Nino peak exactly where theorists expected volcanic cooling. The volcanologists who have not read my book are still scratching their heads about it. Fact is that all so-called “volcanic cooling” incidents are nothing more than accidental coincidence of an expected cooling site with an existent La Nina cooling. Coincidence is determined by chance because volcanism and occurrence of ENSO phases are independent of one another. As a result, it is possible for some volcanoes to find a La Nina to call its own while others just get stuck with an El Nino like El Chichon did and are jipped. To evaluate the situation you have to know accurately where ENSO peaks and valleys are located.
izen says:
March 11, 2014 at 9:08 am
@- Bruce Cobb
“” We can’t actually measure it, nor do we know how it gets there, or why it switches from heating the atmosphere to heating the deep oceans, but we “know” it’s there.”
We know its there because we can, and have measured the continued expansion of the oceans for the last ~15 years and it is not magic but again a measured increase in pacific winds.
All these processes are objhectively observable and recorded just a short google from your desktop- (grin)”
But none of this has anything to do with the postulated “man made CO2” that is now considered by the US EPA to be a “pollutant”.
Hansen did an exercise on Pinatubo, which suggested maybe a global cooling of up to 0.3C for the first two years, then gradually tailing off over the next two or three.
http://www.giss.nasa.gov/research/briefs/hansen_02/
What I have read of studies that attempt to impute climatic effects to volcanic effects seems ignore many elements of an eruption that individually and collectively could have effects on weather. Each volcano, and to a lesser degree each eruption will have distinct chemical signatures. This fact is used in geology to track the extent of volcanic ash plumes. This fact is commonly used by geologists, archaeologists and paleontologists as an important tool. If the age of an eruption is known, the traces of ash can be used to help to date geological and pedological contexts. The chemistry of the irruption may very well have multiple transient effects on atmospheric chemistry and aerosols, and these effects might even tend to cancel each other, e.g. sulphuric acid and CO2 (depending on how effective CO2 really is).
Then there is the location of a volcano. An eruption that injects irruptive output into a jet stream may very well have a far greater geographical reach than one that doesn’t. Smaller VEI irruptions are just as likely to be emitting substances such as sulphuric acid as larger eruptions and the cumulative effects of the smaller irruptions may be as great or greater than on very large irruption. So, it seems at least plausible that the varying annual frequency of smaller volcanic events may have a cumulative effect on weather patterns that has not been discussed in any detail. Also, it seems reasonable to hypothesize that H2SO4 has a greater effect than volcanic ash would, since it is emitted as vapor, while the ash, as a mineral solid will settle out far more quickly. Another consideration is the irruptive history of a volcano in the years, months and weeks leading up to and following a high VEI event. These periods are very likely to have an influence on weather events if volcanic action really does influence weather. In short, attempting to identify “point” effects time and recovery periods is quite possibly pointless – pun intended.
Steven Mosher says:
March 11, 2014 at 9:18 am
Egads, Mosh, you are easily discouraged. When a scientist says something is possible, I usually believe them. But when a scientist says something is not possible … well, I reserve judgement.
In any case, your claim seems to be that the volcano effect is so tiny that it is lost in the noise. Which is certainly true, and that is the main point of this post as well as many of my own posts … but we have methods to deal with that.
An obvious method is to “stack” the records of the various volcanoes to average out the noise. I’ve done that exercise, as did Greg Goodman above. We came to the same conclusion—the effect of eruptions on global temperature is measurable but very small …
Another method is that we have long-term records of volcanic sulfates in the ice cores. This allows us to investigate longer-term interactions of volcanoes and temperature. I discuss this type of volcano/temperature analysis in Dronning Maud Meets the Little Ice Age.
So while the signal is indeed small as you point out, do not lose all hope … ve haff vays …
w.
Sorry, confusion of figure assignments. It is not your Figure 1 but Willis’ Figure 2 in your reference that the description in my comment refers to. Comes from jumping around too much. Along this line, your Figure 4 also shows absence of tropospheric cooling in CET beyond random variations, even for huge eruptions like Tambora. I had been wondering about that one and now I see that it fits in with rest.
Paul Homewood says onMarch 11, 2014 at 10:04 am:
“Hansen did an exercise on Pinatubo, which suggested maybe a global cooling of up to 0.3C for the first two years, then gradually tailing off over the next two or three.”
Paul – Hansen is ignorant of many things, one of which is volcanic cooling. That is not the worst mistake he made. His worst is the claim to the Senate in 1988 that he had discovered greenhouse warming. He discovered no such thing. What he did is to show a rising temperature graph that started in 1880 and peaked in May 1988. That was the highest temperature peak in 100 years, he said. According to him, there was only a one percent chance that this could happen by chance alone. Hence, it followed from this that greenhouse warming had arrived. But if you check existing temperature records you find no hundred year peak there because May 1988 is part of an El Nino peak. There are five El Nino peaks in a row in the eighties and nineties and his is the middle one of the five. You don’t have to be a rocket scientist to understand that calling an El Nino peak the culmination of a hundred years of warming makes no sense if there is a new El Nino formed every five years.
To Neil: The problem is that the VEI is not enough to describe volcanic activity. There are two more important features (1) was is a stratospheric eruption yes/no and (2) the crater diameters. Please take them into account. There are Holocene craters of 20 km diameter, which do show a significant temp drop. If you fiddle with the small stuff only, you get the small stuff temp drop only…But your conclusions are wrong concerning the big stuff, which you left out on purpose….Cheers. JS
climatereason says:
March 11, 2014 at 8:52 am
Tony, thanks much for this reply. It will shed light not just on your contributions but on those of several others who also favor the CET record.
“Submarine eruptions are a type of volcanic eruption that occurs underwater. An estimated 75% of the total volcanic eruptive volume is generated by submarine eruptions near mid ocean ridges alone, however because of the problems associated with detecting deep sea volcanics, they remained virtually unknown until advances in the 1990s made it possible to observe them.”
From Wikipedia
a b Chadwick, Bill (10 January 2006). “Recent Submarine Volcanic Eruptions”
The term “observe” is used lightly here as the supposed obsevations are accoustical in nature and rely upon related earthquake activity which may or may not accompany these eruptions. These would seem to be a very large part of the volcanic ball game which is not included in any of the statistical over massage of volcanic data I have seen on either side of the climate wars.
Joachim says:
March 11, 2014 at 11:56 am
Oh, don’t be a tease. Either give us the exact dates of the volcanoes you are talking about and the temperature dataset that shows a “significant temperature drop” from their eruptions, or go home.
“Cheers”? You accuse Neal of scientific malfeasance without a scrap of evidence to back up your nasty accusations, and you close with “Cheers”?
On second though … just go home …. Cheers,
w.
Arno Arrak says:
March 11, 2014 at 10:45 am
Sure ‘nuf … here’s my analysis of Hansen’s claims …
w.
The Economist magazine has (finally) acknowledged a ‘pause’ in global warming.
http://www.economist.com/news/science-and-technology/21598610-slowdown-rising-temperatures-over-past-15-years-goes-being
It ascribes the pause to aerosols, the solar cycle, and by ocean winds and currents.
“Gavin Schmidt and two colleagues at NASA’s Goddard Institute quantify the effects of these trends in Nature Geoscience. They argue that climate models underplay the delayed and subdued solar cycle. They think the models do not fully account for the effects of pollution (specifically, nitrate pollution and indirect effects like interactions between aerosols and clouds). And they claim that the impact of volcanic activity since 2000 has been greater than previously thought.”
Steven Mosher says:
March 11, 2014 at 9:18 am
You wrote in part and briefly: “. . . unless you have a large sample the noise on either side of the eruption [this] will make a good estimate hard to come by.” ( [this] inserted )
I believe the rest of your comment is consistent with that. If not, please, correct me.
This means, as far as I can tell, the signature of volcanic eruptions is too small to be easily distinguished from the surrounding noise. Or, putting it another way, the volcanic signature is necessarily minor. This, of course, is the thrust of the post.
Am I wrong?
Would it not be possible to overlay multiple events properly scaled to extract the volcanic signal more accurately?
Thanks for continuing to comment and taking the time to actually say something.
I am as always a confirmed skeptic on CAGW from the time of the previous horrible coming ice age.
I was studying graduate units regarding Thera and Pompeii. Thera erupted around 1600 BC – 1300 BC (there’s disagreements between archaeologists) and did change the climate for a number of years. So did Vesuvius in 1600 BC. Mount Ararat too. One Chinese chronicle reports seven years of drought, frost in summer, and the sun was obliterated for years. So a huge Volcanic eruption like Thera can affect the climate for a number of years and cause great movements of people seeking a living from other peoples resources, like the sea people. I can not understand why people still live in Naples and near Mt Vesuvius, because when it eventually goes up, those not able to evacuate will be covered like the Pompeiians.
One might conclude from the two really heroic eruptions in figure 2 that the first ushered in the medieval warm period, and the second the modern warm period.
Maybe the particulates are just a short term effect (there may be meaning in the simple vs. multi phase recoveries). Maybe the real dude is the water, by far the largest volcanic ejecta, and just plain ol’ mass.
Don’t get me started on the correlation between Large Igneous Provinces and temperature…
The CET does not respond much to anything, just like most things from England.
“… indeed temperatures had dropped sharply several years before 1257 and recovered very quickly afterwards.”
Ed Caryl (http://notrickszone.com/2013/12/22/disappearing-excuses-aerosols-likely-not-behind-the-warming-pause/) : “… El Chichon and Mt. Pinatubo pre-1995 resulted in warming …”
Why “… very quickly afterwards.”, “… El Chichon and Mt. Pinatubo pre-1995 resulted in warming …”?
Climate response to volcanic eruptions is very diverse (I recommend the book: Climate and ecosystems, D. Schimel, 2013).
I. CLAW hypothesis.
Initially, volcanic dust fertilize the ocean = increase amount of aerosols = increase cloud cover. Volcanoes destroy stratospheric ozone, however. Ozone in the stratosphere long after the eruption remains at a low level (his amount increasing very slowly). Few stratospheric ozone – effect: an increase (even double) ULV in the troposphere. ULV destroys phytoplankton = cloud cover decreases …
Craig Idso (http://ourchangingclimate.wordpress.com/tag/craig-idso/) says it’s a very risky hypothesis, but …
Ozone depletion: ultraviolet radiation and phytoplankton biology in antarctic waters, Smith RC, Prézelin BB, Baker KS, Bidigare RR, Boucher NP, Coley T, Karentz D, MacIntyre S, Matlick HA, Menzies D, et al., 2009. (http://www.ciesin.org/docs/011-450/011-450.html) “A minimum 6 to 12 percent reduction in primary production associated with O3 depletion was estimated …”
(http://www.antarctica.gov.au/__data/assets/pdf_file/0016/22453/ml_390854214351852_00620phytoplankton_krill.pdf): “New research suggests that the growth of phytoplankton is reduced by 56% when stratospheric ozone drops below 17% …”
(http://media.tumblr.com/b3343931a391a8b77f6eb25aa926babd/tumblr_inline_muiwu6tBH71ro0ix8.jpg) – here we see, that the increase in phytoplankton most often precedes the decrease in temperature.
II. El Nino. Jochum et al, 2010. (Quantification of the Feedback between Phytoplankton and ENSO in the Community Climate System Model http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3254.1) shows that ENSO significantly influenced on phytoplankton, and phytoplankton also significantly affects on ENSO …
III. Stratospheric ozone also affects the content of water vapor in the stratosphere – cloud cover (…).
Conclusion: volcanic eruptions cools and maybe also warms the troposphere. The balance depends on many factors and, unfortunately, is not known.
Interesting. I’m not sure how valid the data from ancient history is, but, it confirms what many of us have found, already. For those who may be curious, I recently plotted all of last century’s VEI 5s and 6s against HadCrut3. There’s no distinguishable difference after the eruptions and the normal noise that we have. Sure, locally significant, but, very transient, but, on a global scale, one can’t see where it does anything. You can see the plot here, http://suyts.wordpress.com/2014/02/24/good-greif-time-for-another-volcano-post/ In it, there’s a link to some close up time scale snap shots I did earlier. IDK, I can’t see any definitive drop in temps pattern from the eruptions. Sure, there are some, but, there are also temp increases immediately following some. It’s just not there.
Neil
CET is the temperature of the Midlands region of England. It’s 11,000 sq. mi. That’s 0.006% of earth surface area. Not representative of global temperature. But assuming it is representative, your data show volcanic eruptions have big impact on global temperature. The average decrease in global temperature for one-year periods since 1950 is -0.09 C. Krakatau is over 4x larger and Pinatubo is over 11x larger based on your data.
Dr. Strangelove says:
March 12, 2014 at 6:57 pm
Actually, it is positively correlated with global temperature, and the correlation isn’t all that bad …
w.
Willis
If we can substitute CET for global temperature, that would be great! We don’t need thousands of weather stations around the world. No need to worry about UHI and improper siting of stations. And it shows volcanic eruptions have big cooling effect on the short term.
Dr. Strangelove says:
March 13, 2014 at 12:56 am
Well way back when, CET is about all you got so I guess for log history stuff you don’t have much of a choice. Bring in the time machine that will allow us to go back and place some more stations and this would all get a lot easier.
I suppose you could try and link Mount Etna, Italy—1669, one of the 10 largest volcanos in history (http://www.randomhistory.com/history-of-volcanoes.html) with a downturn in the CET
http://climatedatablog.wordpress.com/cet/
but unfortunately the temps were already on their way down so, unless they just knew what was about to happen, that seems unlikely.
The other ones that occurred in the more recent history do not seem to match either.
Richard
Just because you don’t have a time machine is no excuse to do lousy science. I would rather say I don’t know than pretend I know. Anyway in this case the result is as expected – cooling – but that could be just due to chance.
Dr. Strangelove says:
March 13, 2014 at 6:20 pm
http://climatedatablog.wordpress.com/cet/
is some cooling! It’s starting to look lie a set of bookends and with no volcanos that can be easily attributed to either end.
CET has always been considered to be a fairly good proxy for the rest of Europe given its position to the West, i.e. at the windward end. That is not a given but it has held quite well in the past.
Clearly, volcanic aerosols intercept and store up solar radiant heat and release it afterwards, increasing the net temperature. Eruptions are good for you!